Light energy harvesting, which wirelessly charges an existing battery by converting light energy to electric power, is a technology inevitably required to establish the Internet of things (IoT), ubiquitous sensor networks (USN), wireless sensor networks (WSN) and the like and acts as a semi-permanent power source supplied to diverse electronic devices related to such fields.
Accordingly, the light energy harvesting technology is required to be microminiaturized and integrated. Although some studies have shown attempts to manufacture a light energy conversion device that is similar to an integrated solar cell (ISC) by employing P-N junction photodiode technique from the CMOS process in order to integrate the light energy conversion device into another circuit, such a photodiode exhibits a low photoelectric conversion efficiency, which is not adequate to supply the circuits in the chip with sufficient power. Furthermore, it is a long way to go to fully integrate a solar cell process with a standard CMOS process.
The present invention relates to a method and technical thoughts pertinent to it to provide a pixelated solar cell system on chip (SOC) on the basis of and improving the registered patents, “Unit Pixel of Image Sensor and Photo Detector Thereof” (U.S. Pat. No. 8,569,806B2, U.S. Pat. No. 8,610,234B2 and U.S. Pat. No. 8,669,599B2). To this purpose, the structure and operation of a photo detector and a pixelated solar cell manufactured via a standard CMOS process will be described and a method will be proposed where a pixel of a solar cell thus manufactured shares a single cell with a pixel of an image sensor so that each function may be selected as necessary.